Addition Within 20 (Number Lines) — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 5 + 6 = 11
Start at 5 on the number line and jump 6 spaces to land on 11.
2. 9 + 3 = 12
From 9, count forward just 3 more: 10, 11, 12. You reach 12 quickly because 9 is close to 10.
3. 8 + 6 = 14
Start at 8 and hop 6 spaces forward on the number line. You pass 10 and stop at 14.
4. 7 + 4 = 11
From 7, jump ahead 4 spaces: 8, 9, 10, 11. You land on 11.
5. 6 + 8 = 14
Begin at 6 and count 8 spaces forward to reach 14. Starting at the bigger number (8) and adding 6 gives the same answer.
6. 9 + 7 = 16
Start at 9 and jump 7 spaces ahead on the number line. You pass through 10 and land on 16.
7. 5 + 9 = 14
From 5, hop forward 9 spaces to reach 14. You can also start at 9 and add 5 to get 14 faster.
8. 8 + 5 = 13
Start at 8 on the number line and count up 5: 9, 10, 11, 12, 13. The answer is 13.
9. 7 + 8 = 15
From 7, jump forward 8 spaces on the number line. You go past 10 and land on 15.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
9 + 9
→ 18
11
6 + 5
→ 11
13
8 + 6
→ 14
14
7 + 6
→ 13
18
Each addition problem goes with its sum: 9 + 9 = 18 (a double), 6 + 5 = 11, 8 + 6 = 14, and 7 + 6 = 13. Count on the number line to verify.